Systems are known in the prior art wherein temperature transducers are used to control a time base multiplier which modulates a high density meter pulse train. This is described in the Kovaks U.S. Pat. No. 3,729,995. In another prior art system, an oscillator is gated by integrating and level detecting circuits. This is shown in the Stroman U.S. Pat. No. 3,588,481. The McKinley U.S. Pat. No. 3,854,038 shows the use of high frequency transducers in combination with an oscillator which is gated by the low speed meter pulse.
In general, the prior art systems, of which the above are representative, demand a relatively large amount of power and cannot be used on battery powered service. This is a serious disadvantage, especially where remote maintenance-free installations are required.